Tissue ablation device and method of use

ABSTRACT

A tissue ablation device creates long linear lesions along a body space wall of an animal, and primarily between adjacent pulmonary vein ostia in a left atrial wall. An ablation element includes first and second ends that are bordered by first and second anchors. The anchors are adapted to secure the ablation element ends at predetermined first and second locations along the body space wall such that the ablation element is adapted to ablate an elongate region of tissue between those locations. The anchors may be guidewire tracking members, each including a bore adapted to receive and track over a guidewire, and may anchor within adjacent pulmonary vein ostia when the engaged guidewires are positioned within the respective veins. Stop members may be provided on the guidewires and may be adapted for positioning the relative anchors or for forcing the anchors to fit snugly within the vein ostia. A conduit passageway through the catheter houses a stiffening stylet which may be advanced into the region of the ablation element in order to impart a shape to that element to conform it to a predetermined region of anatomy, or to stiffen the underlying catheter in order to advance the assembly into remote anatomy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of copending application Ser. No.10/233,264, filed on Aug. 30, 2002, incorporated herein by reference,which is a continuation of copending application Ser. No. 09/357,184filed on Jul. 19, 1999, now U.S. Pat. No. 6,471,697, incorporated hereinby reference, which is a continuation of copending application Ser. No.08/853,861 filed on May 9, 1997, now U.S. Pat. No. 5,971,983,incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is a surgical device. More particularly, it is amedical catheter assembly that has an ablation element which is adaptedto have its two ends anchored at predetermined locations on a body spacewall such that the ablation element is adapted to firmly contact thelength of tissue between predetermined locations for the purpose offorming a long linear lesion therebetween.

2. Description of Related Art

Atrial Fibrillation

Cardiac arrhythmias, and atrial fibrillation in particular, remain apersistent medical condition in modern society. In the United Statesalone, approximately 1% of the total adult population is afflicted byatrial fibrillation, currently more than 2.5 million people, withprevalence increasing as a function of age. The resulting loss of bloodflow due to incomplete cardiac contractions along with a rapid heartrate can lead to shortness of breath, dizziness, limited physicalendurance, and chest pains. Persistence of atrial fibrillation rendersan individual susceptible to congestive heart failure, stroke, otherthromboembolic events, and myocardial ischemia. Considerable informationis evolving regarding the conditions of the heart which contribute tothe appearance of atrial fibrillation, factors which may be exacerbatedby stress, anxiety, high blood pressure, heart valve disorders, andheart muscle dysfunction. An initial overview of the clinical phenomenaassociated with atrial arrhythmia is as follows.

The mammalian heart is composed of three different categories of cardiactissue namely, atrial, ventricular, and excitatory conduction types.Normally, the atrial and ventricular muscles of the heart areelectrically excited in a synchronous, patterned fashion. The cardiaccycle commences with the generation of action potentials by thesino-atrial (SA) node, located in the lateral wall of the right atrium.These action potentials propagate through the atrial chamber, possiblyalong preferential conduction pathways leading to the atrioventricular(AV) node. Potentials emanating from the AV node travel through theHis-Purkinje bundle to the ventricular tissue, causing a synchronouscontraction of the ventricles following that of the atria.

Pathological conditions of the cardiac tissue may lead to asynchronouscardiac rhythms, resulting in an overall elevation in the heart rate,inclusive of paroxysmal or chronic tachycardias. Tachycardias mayinitiate in the AV node, the bundle of His, or more generally in theatrial or ventricular tissues. The aforementioned tachycardias maymanifest as a multiwavelet reentrant mechanism, resulting inasynchronous eddies of electrical impulses scattered about the atrialchamber. The fibrillation may also be more focal in nature, caused bythe rapid, repetitive firing of an isolated center within the atria, butso rapidly that the remainder of the atrium cannot follow in asynchronized fashion.

Presently, many categories of tachycardia may be detected using theelectrocardiogram (EKG). An alternative, more sensitive procedurecommonly used to detect localized aberrations in electrical activity,and thus confirm the presence of arrhythmias such as atrialfibrillation, is the mapping of the cardiac chambers as disclosed inU.S. Pat. Nos. 4,641,649 and 4,699,147 and WO 96/32897.

Numerous cardiac arrhythmias, such as atrial fibrillation, were oncethought untreatable except by pharmacological or surgical intervention,both capable of manifesting undesirable side effects. Recently, theemergence of less invasive catheter ablation methods have expanded thefield of cardiac electrophysiology to provide limited percutaneoussolutions to the medical conditions just described. A brief descriptionof the aforementioned conventional therapies for atrial fibrillation andapproaches to cardiac ablation thereof is found below.

Regimes of Conventional Treatment

Episodes of tachycardia may be responsive to treatment by antiarrhythmicmedication, as disclosed in U.S. Pat. No. 4,673,563 to Berne et al. andfurther described in U.S. Pat. No. 4,569,801. In addition,pharmacological intervention for treating atrial arrhythmias has beendisclosed in the Hindricks, et al. in “Current Management ofArrhythmias” (1991). However, the administration of such medicationssometimes does not restore normal cardiac hemodynamics, and mayultimately exacerbate the arrhythmic condition through the occurrence ofproarrhythmia.

Specific clinical circumstances may necessitate invasive surgicalintervention for multiwavelet tachycardias, including the placement ofimplantable atrial defibrillators to maintain sinus rhythms as disclosedin U.S. Pat. Nos. 4,316,472; 5,209,229; 5,411,524 or alternatively, bythe mechanical destruction of atrial electrical conduction pathways, asdescribed by Cox, J L et al. in “The surgical treatment of atrialfibrillation. I. Summary” Thoracic and Cardiovascular Surgery 101 (3),pp. 402-405 (1991) or Cox, J L “The surgical treatment of atrialfibrillation. IV. Surgical Technique”, Thoracic and CardiovascularSurgery 101 (4), pp. 584-592 (1991).

Described by the Cox procedure, as referenced above, is a strategy toincur patterned surgical incisions within the atrial chambers, creatinga maze by which propagating electrical waves are extinguished at thelines of suture. In this way, reentrant wavelets are not sustained,arrhythmia cannot persist, and normal sinus rhythm is restored. Curativeefforts for atrial arrhythmias were initially focused on the rightatrium, with mixed results. However, procedures which combine right andleft atrial treatments have been observed to have dramatically increasedsuccess rates. In the left atrium, a common protocol includes verticalincisions from the two superior pulmonary veins and terminating justposterior to the mitral valve annulus, transversing the inferiorpulmonary veins en route. An additional horizontal line also connectsthe superior ends of the two vertical incisions. Thus, the region of thepulmonary vein ostia is isolated from the other atrial tissue. Bysevering electrical conduction pathways within the atrial tissues, thefibrillatory process is eliminated.

Transcatheter Cardiac Ablation

Alternative, less invasive approaches have recently been adopted for thetreatment of cardiac arrhythmias in a clinical setting. Thesecatheter-based transvascular approaches include procedures andassociated devices for the treatment of ventricular or supraventriculartachycardias, as described in Lesh, M D in “InterventionalElectrophysiology—State of the Art, 1993” American Heart Journal, 126,pp. 686-698 (1993).

The initial approach to the ablative procedure used catheters responsiveto high energy direct current (DC) to either disrupt the AV nodefunction or to create a heart block by disruption of the His bundle.However, it has been more recently observed that radio frequency (RF) isoften a more desirable energy source as disclosed in WO 93/20770.Alternative ablation techniques have also been disclosed. For example,an ablative catheter responsive to microwave frequencies is described inWO 93/20767. Other catheter based ablation technologies which have alsobeen disclosed to render the aberrant cells electrically silent includefreezing, ultrasound, and laser energy as disclosed in U.S. Pat. Nos.5,147,355; 5,156,157 and 5,104,393, respectively.

Ablation procedures have typically involved the incremental applicationof electrical energy to the endocardium to form focal lesions tointerrupt the inappropriate conduction pathways. Methods and devices forusing percutaneous ablative techniques intended to remedy cardiacfibrillation or arrhythmias have been disclosed in U.S. Pat. Nos.5,231,995; 5,487,385; WO 94/21165 and WO 96/10961 in addition to U.S.Pat. Nos. 5,228,442 and 5,324,284 to Imran. The disclosures of thesereferences are herein incorporated in their entirety by referencethereto.

For some types of cardiac arrhythmias, a focal ablative lesion (i.e.,5-8 mm in diameter) is adequate to sever inappropriate conductionpathways such as those associated with the Wolff-Parkinson-Whitesyndrome. However, such focal lesions are not appropriate for most casesof atrial fibrillation which involve multiple reentrant loops. Theseexcitation waves would simply go around a focal ablative lesion. Thus,as in the surgical “maze” procedure, long linear lesions are required inorder to segment the atrium to block the wave fronts associated withmost forms of atrial fibrillation.

Certain particular catheter based technologies exist which are intendedto emulate all or a portion thereof, the incision patterns of the mazeprocedure using curvilinear catheters. The use of such catheters inablative procedures is disclosed in Avitall et al., in “Physics andEngineering of Transcatheter Tissue Ablation”, Journal of AmericanCollege of Cardiology, Volume 22, No. 3: 921-932 (1993). In addition,the use of transcatheter ablation to remedy atrial fibrillation in aclinical setting, specifically by the use of a percutaneously introducedablation catheter (with either a 7F deflectable 4-mm tip withthermocoupler; Cordis Webster, Miami, F L, or a woven Dacron 14 by 4-mmmultielectrode from Bard Electrophysiology, Tewksbury, Mass.) isdescribed in Haissaguerre, et al. in “Right and Left AtrialRadiofrequency Catheter Therapy of Paroxysmal Atrial Fibrillation” inJournal of Cardiovascular Electrophysiology 7(12), pp. 1132-1144 (1996).These articles are herein incorporated in their entirety by referencethereto.

The aforementioned references disclose methods which use a sequentialapplication of energy from a point on a catheter, which is remotelymanipulated, to ostensibly create an ablation maze according to apredetermined pattern. However, this process may fail to producecontinuous, transmural lesions, thus leaving the opportunity for thereentrant circuits to reappear. In addition, minimal means are availablein these embodiments for steering the catheters to anatomic sites ofinterest such as the pulmonary veins.

Catheter Positioning Technology

Many different types of catheters have been disclosed for guiding,accessing, and positioning at a predetermined location within the bodyfor the purposes of performing a medical treatment.

A number of steerable catheter systems, exhibiting a plurality ofcurvatures at their distal end, have been devised which may beintroduced into the blood vasculature or other lumen, navigating themany passageways, ultimately reaching previously inaccessible areaswithin the cardiac chamber without invasive surgery. For example,catheters with complex curvatures and preshaped member loops have beendevised for placement in the cardiac chambers as described in U.S. Pat.No. 4,117,836 (left coronary artery); U.S. Pat. No. 5,195,990 (aorta);the right ventricle in U.S. Pat. No. 4,882,777; U.S. Pat. No. 4,033,031discloses a catheter design for access of the pericardial space.Additional examples of intravascular steerable catheters used in cardiacablative procedures are disclosed in U.S. Pat. Nos. 4,898,591 and5,231,994. The disclosures of these references are herein incorporatedin their entirety by reference thereto.

One class of catheters exemplifies steerable guidewires as rails. Ofthese, some are “over-the-wire” types of catheters which have lumenssubstantially extending along their entire length and which are adaptedto track over a guidewire. Other “guidewire tracking”-types of cathetershave also been disclosed, generally referred to “rapid-exchange” or“monorail” catheters, which have only a distal region of the catheterlength adapted to track over a guidewire. This type of catheter benefitsin the ability to separately control proximal regions of both theguidewire and also the catheter externally of the body, since only thedistal region of the catheter is coaxial over the guidewire. Examples ofthese types of catheters are disclosed in U.S. Pat. Nos. 5,300,085 and5,501,227 to Yock.

Furthermore, the use of particular guiding sheath designs for use inablation procedures in both the right and/or left atrial chambers aredisclosed in U.S. Pat. Nos. 5,427,119; 5,497,119; 5,564,440; 5,575,766to Swartz et al. In particular, the aforementioned art describes amethod which requires a real time repositioning of a point source ofenergy along a preferred pathway in the moving wall of a beating atrium.In doing so, a remote percutaneous manipulation of the device isrequired using only the means of X-ray fluoroscopy for visualizingcatheter location. Moreover, the use of a monorail catheter with severaldeployable shapes for the purposes of creating incremental lesions alonga predetermined linear path in the right atrium, accomplished bysustaining the elongate ablation element at a predetermined locationalong a body space wall, is disclosed in U.S. Pat. No. 5,487,385 toAvitall.

Several catheter designs have also incorporated a plurality of distallylocated mechanisms to stabilize the catheter, thus enabling preciseplacement of the ablation electrodes within a cardiac chamber. Suchtechnologies may include the use of a stop and/or a balloon as disclosedin U.S. Pat. Nos. 5,487,385 and 5,496,346, respectively, along theguidewire contained in the catheter. Alternatively, a catheter adaptedto be mechanically retained in a fixed position within a vessel lumen isdisclosed in U.S. Pat. No. 5,509,500 to Kirkman. Furthermore, thepositioning of a catheter within the heart using a distally locatedinflatable balloon device during ablation procedures has been disclosedin U.S. Pat. No. 5,571,159 to Alt and U.S. Pat. No. 4,762,129 to Bonzel.

None of the cited references discloses a tissue ablation device havingan ablation element having anchors at each of two ends for anchoring theends to first and second predetermined locations along a body space wallin order to secure the length of the ablation element to the tissuebetween those locations for ablating a long linear lesion.

None of the cited references discloses a kit of multiple ablationcatheters, each having a unique ablation length which may be chosen foruse in the formation of a long linear lesion between two anatomicanchoring points, such as the two pulmonary vein ostia, according to themeasured length of the distance between those anatomic sites in apatient.

None of the cited references discloses a catheter having a means forselectively positioning an intermediate region of the catheter locatedproximally of the distal tip, nor do they disclose a catheter having aguidewire tracking region with both proximal and distal guidewire portspositioned on that intermediate catheter region.

In addition, none of the cited references discloses a catheter devicethat provides a multirail guidewire tracking capability at variouspositions along the catheter length.

Still further, none of the cited references discloses a tissue ablationdevice assembly having an elongate ablation element with at least onesuctioning port along its length which is coupled to a suction source inorder to anchor the ablation element to tissue along a body space wall.

BRIEF SUMMARY OF THE INVENTION

The present invention is a medical device assembly for creating longlinear lesions in a body space wall which defines at least in part abody space in an animal.

One aspect of the invention is an ablation catheter assembly whichincludes an elongate body having proximal and distal end portions and anablation element on the distal end portion that is adapted to ablatetissue when coupled to an ablation actuator. The ablation element hasfirst and second ends. A first anchor is positioned adjacent the firstend and is adapted to secure the first end at a predetermined firstlocation along the body space wall. A second anchor is positionedadjacent the second end and is adapted to secure the second end at apredetermined second location along the body space wall.

By securing the first and second ends of the ablation element in thisvariation to the predetermined locations with the anchors, the ablationelement is adapted to substantially contact a length of tissue adjacentto the ablation element and between the first and second locationswithout substantially repositioning the distal end portion of theelongate body.

In one variation of this assembly, at least one of the first and secondanchors is a guidewire tracking member which has a bore that is adaptedto advance the adjacent end of the ablation element over a guidewire andinto an ostium of a pulmonary vein along a left arterial wall when theguidewire is positioned within that vein. Further to this variation,when both anchors are guidewire tracking members, the ablation elementmay be anchored at each of its ends over wires in adjacent pulmonaryvein ostia and is adapted to substantially contact and ablate a regionof arterial wall tissue extending between those adjacent ostia.

In a further variation of this assembly, a radially enlarged stop memberis provided on at least one of the guidewires. When the stop member ispositioned distally on the wire relative to the guidewire trackingmember, it provides a preselected position against which the guidewiretracking member may be advanced. When the stop member is positionedproximally on the wire relative to the guidewire tracking member, theguidewire may be used to push the stop against the proximal port of theguidewire tracking member to thereby force the guidewire tracking membersnugly into the pulmonary vein.

Another aspect of the invention is a kit of ablation catheters forcreating long linear lesions in the tissue of a body space wall which atleast in part defines a body space in an animal. This kit includes inpackaged combination a plurality of ablation catheters, each having aproximal end portion, a distal end portion, and an ablation element inthe region of the distal end portion. The ablation element of eachablation catheter has first and second ends which are each bordered byan anchor adapted to secure the adjacent end to a predetermined locationalong a body space wall. Furthermore, the ablation element of eachablation catheter has a different length than the ablation element ofthe other ablation catheters. An ablation catheter having an ablationelement with a particular length may be chosen from this kit based uponthe measured distance between adjacent pulmonary vein ostia in apatient's left atrial wall.

Another aspect of the invention is a medical device assembly which isadapted for positioning multiple portions thereof at multiplepredetermined locations within a body space of an animal. This assemblyincludes an elongate body having a proximal end portion, a distal endportion, and an intermediate guidewire tracking member located betweenthe proximal and distal end portions. The intermediate guidewiretracking member forms an intermediate bore with first and secondintermediate bore ends. The bore is adapted to slideably receive aguidewire through the first intermediate bore end from a positionexternally of the elongate body and to direct the guidewire to extendfrom the second intermediate bore end also externally of the elongatebody.

In one variation of this assembly, an ablation element is provided onthe distal end portion and has a proximal end that is adjacent to theintermediate guidewire tracking member. In another variation of thisassembly, a guidewire is provided which has a radially enlarged stopmember which is adapted to engage the bore of the intermediate guidewiretracking member and limit the movement of the guidewire relative to thatbore.

Another aspect of the invention is a method for positioning anintermediate guidewire tracking member of an elongate body of a medicaldevice assembly at a predetermined location within a body space. Theintermediate guidewire tracking member forms a bore which is adapted toreceive a guidewire and which is located between a proximal end portionand a distal end portion of the elongate body. The method includes thesteps of: (1) inserting a guidewire into the bore in the region of theintermediate portion from a position externally of the elongate body;(2) advancing the guidewire through the bore; and (3) extending theguidewire from the bore and externally of the elongate body in theregion of the intermediate portion.

Another aspect of the invention is a method for creating a long linearlesion in the tissue between first and second predetermined locationsalong the surface of a body space wall. The method includes the stepsof: (1) measuring the distance between the first and secondpredetermined locations; (2) choosing a medical device assembly havingan ablation element with first and second length having a predeterminedlength based upon the measured distance; (3) anchoring the first andsecond ends of the ablation element at the first and secondpredetermined locations; and (4) ablating the tissue between the firstand second predetermined locations to form a long linear lesiontherebetween.

Another aspect of the current invention is a method for creating longlinear lesions in a tissue wall which defines at least a portion of abody space. This method uses a medical device that has an elongate bodywith a distal end portion that includes an ablation element adapted toablate tissue adjacent thereto when coupled to an ablation actuator.This method includes the steps of: (1) securing a first end of theablation element at a first location along the tissue wall; (2) securinga second end of the ablation element at a second location along thetissue wall; and (3) activating the ablation element with the ablationactuator to ablate tissue adjacent thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood by reference to thefollowing drawings which are for illustrative purposes only:

FIG. 1 is a perspective view of one atrial lesioning catheter assemblyof the present invention.

FIGS. 2A-B show partial exploded top and side perspective views,respectively, of the intermediate guidewire tracking member of thecatheter assembly shown in FIG. 1.

FIGS. 2C-D show a side sectional view and a cross sectional view of onevariation for the intermediate guidewire tracking member, taken alonglines 2C-2C from FIGS. 2A and 2D-2D from FIG. 2B, respectively.

FIG. 2E shows a cross sectional view of another variation for theintermediate guidewire tracking member shown in FIG. 2B and is takenalong lines 2E-2E.

FIG. 3 shows a perspective view of the atrial lesioning catheterassembly of FIG. 1, shown in use with two opposite ends of an ablationelement anchored in adjacent left and right superior pulmonary veinostia along a left atrial wall and prior to forming a long linear lesionbetween those ostia.

FIG. 4 shows a similar perspective view of the atrial lesioning deviceassembly shown in FIG. 3, although showing a further variation of theintermediate guidewire tracking member that anchors the proximal end ofthe ablation element adjacent the right superior pulmonary vein ostium.

FIG. 5 shows a similar perspective view of the atrial lesioning deviceassembly shown in FIG. 3, although showing another variation for thedistal guidewire tracking member that anchors the distal end of theablation element adjacent the left superior pulmonary vein ostium.

FIG. 6 shows a similar perspective view of the atrial lesioning deviceassembly shown in FIG. 3, although showing yet another anchoringvariation at the distal end of the ablation element adjacent the leftsuperior pulmonary vein ostium.

FIG. 7 shows a similar perspective view of the atrial lesioning deviceassembly shown in FIG. 5, although showing a further variation for theintermediate guidewire tracking member that anchors the proximal end ofthe ablation element at the right superior pulmonary vein ostium.

FIG. 8 shows a similar perspective view of the atrial lesioning deviceassembly shown in FIG. 7, although showing yet a further variation forthe intermediate guidewire tracking member that anchors the proximal endof the ablation element at the right superior pulmonary vein ostium.

FIG. 9A shows a similar perspective view of the atrial lesioning deviceassembly shown in FIG. 7, although showing yet a further variation forthe distal guidewire tracking member that anchors the distal end of theablation element at the left superior pulmonary vein ostium.

FIGS. 9B-C shows a similar perspective view as that shown in FIG. 9A,although showing yet a further anchoring variation at the distal end ofthe ablation element, shown in two modes of operation, respectively.

FIG. 10A shows an exploded partial perspective view of a furthervariation of the atrial lesioning device assembly shown in FIG. 7, andshows a series of fluid ports located along the length of the ablationelement.

FIGS. 10B-E show sequential cross-sectional views of the ablationelement shown in FIG. 10A, taken along lines 10B-10B; 10C-10C; 10D-10D;and 10E-10E, respectively.

FIG. 10F shows an exploded partial perspective view of yet a furthervariation for the ablation element region of the ablation deviceassembly shown in FIG. 10A.

FIG. 11 shows a side sectional view of one ablation element variationfor use in the ablation device assembly of the current invention andshows each of a plurality of thermistors positioned beneath an electrodefor use in monitoring the temperature adjacent the electrode duringablation.

FIG. 12 shows a side sectional view of another ablation elementvariation for use in the ablation device assembly of the currentinvention and shows each of a plurality of thermocouples positionedbeneath an electrode for use in monitoring the temperature adjacent theelectrode during ablation.

FIG. 13 shows an exploded perspective view of one thermocouple andelectrode used in the ablation element shown in FIG. 12.

FIG. 14 shows a side sectional view of a similar ablation elementvariation for use in the ablation device assembly of the currentinvention as that shown in FIG. 12, although showing the plurality ofthermocouples positioned between ablation electrodes.

FIGS. 15A-B show schematical views of alternative feedback controlvariations for use in the ablation actuator of the ablation deviceassembly of the current invention.

FIG. 16 provides a perspective view of the ablation device assemblyshown in FIG. 5 during use in sequentially forming long linear lesionsbetween the left superior and inferior pulmonary vein ostia.

FIG. 17 provides a perspective view of the same ablation device assemblyshown in FIG. 16, positioned in the right superior and inferiorpulmonary vein ostia, shown after an initial formation of a long linearlesion between the left and right superior vein ostia according to theablation element anchoring shown in FIG. 5.

FIG. 18 shows a perspective view of a further atrial lesioning deviceassembly according to the current invention, showing the ablationelement of a first ablation device positioned adjacent to a leftinferior pulmonary vein ostia, and also showing in shadowed view theablation element of a second electrode device positioned within thecoronary sinus and adjacent to the first ablation element and the mitralvalve annulus.

FIG. 19 shows a similar perspective view of the atrial lesioning deviceassembly shown in FIG. 18, although showing the ablation element of thefirst ablation device repositioned in the right inferior pulmonary veinostium, and also showing the ablation element of the second ablationdevice repositioned along the coronary sinus adjacent to the firstablation element and the mitral valve annulus.

FIG. 20 shows a further embodiment of the ablation device assembly usedin forming multiple long linear lesions during a single positioningevent, wherein a stylet is shown during use to bridge the left superiorand inferior vein ostia in addition to engaging the left mitral valveannulus for the purposes of creating a continuous long linear lesion.

FIG. 21 shows a perspective view of the inner surface of an atrial wallsubsequent to the multiple long linear lesion ablations performedaccording to FIGS. 16-19, or in part according to the multiple longlinear lesions created by the variation shown in FIG. 20.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is herein described by reference to particularlydesirable embodiments shown in the figures. However, the presentinvention broadly provides an elongate ablation element with anchors atmultiple regions of that element, such as at each of its ends, whichallow those ends to be secured at predetermined locations along a bodyspace wall, such as along an atrial wall. In this novel arrangement, theablation element is adapted to firmly contact a continuous length oftissue along the body space wall between the predetermined locations toform a long linear lesion in that tissue.

The term “anchor” is herein intended to mean an element which is atleast in part located in an anchoring region of the device and which isadapted to secure that region at a predetermined location along a bodyspace wall. As such, “anchor” is intended to provide fixation as asecuring means over and above a mere normal force against a singletissue surface which is created by confronting contact between thedevice and the tissue. Examples of suitable “anchors” within theintended meaning include (but are not limited to): an element thatdirectly engages the tissue of the wall at the predetermined locationsuch as by clamping, suctioning, or penetrating that tissue; and aguidewire engaging or tracking member which provides a bore or lumenadapted to track a guidewire through an ostium of a lumen extending fromthe body space wall, thereby penetrating the plane of the body spacewall at a predetermined location at the ostia.

Furthermore, an expandable element, such as an expandable balloon orcage, is considered an anchor to the extent that it radially engages atleast two opposite body space wall portions to secure the expandableelement in place (such as opposite sides of a vessel). To the extentthat the disclosure of the invention below is directed to any oneparticular anchoring element, it is contemplated that other variationsand equivalents such as those described may also be used in addition orin the alternative to that particular element.

The phrase “ablation element” is herein intended to mean an elementwhich is adapted to substantially ablate tissue in a body space wallupon activation by an actuator.

The term “ablation” or derivatives thereof is herein intended to meanthe substantial altering of the mechanical, electrical, chemical, orother structural nature of the tissue. In the context of intracardiacablation applications as shown and described with reference to theembodiments below, “ablation” is intended to mean sufficient altering ofthe tissue properties to substantially block conduction of electricalsignals from or through the ablated cardiac tissue.

The term “element” within the context of “ablation element” is hereinintended to mean a discrete element, such as an electrode, or aplurality of discrete elements, such as a plurality of spacedelectrodes, which are positioned so as to collectively ablate anelongated region of tissue.

Therefore, an “ablation element” within the intended meaning of thecurrent invention may be adapted to ablate tissue in a variety of ways.For example, one suitable “ablation element” may be adapted to emitenergy sufficient to ablate tissue when coupled to and energized by anenergy source. Suitable examples of energy emitting “ablation elements”within this meaning include without limitation: an electrode elementadapted to couple to a direct current (DC) or alternating current (AC)source, such as a radiofrequency (RF) current source; an antenna elementwhich is energized by a microwave energy source; a heating element, suchas a metallic element which is energized by heat such as by convectionor current flow, or a fiber optic element which is heated by light; alight emitting element, such as a fiber optic element which transmitslight sufficient to ablate tissue when coupled to a light source; or anultrasonic element such as an ultrasound crystal element which isadapted to emit ultrasonic sound waves sufficient to ablate tissue whencoupled to a suitable excitation source.

More detailed descriptions of radiofrequency (RF) ablation electrodedesigns which may be suitable in whole or in part as the ablatingelement according to the present invention are disclosed in U.S. Pat.No. 5,209,229 to Gilli; U.S. Pat. No. 5,487,385 to Avitall; and WO96/10961 to Fleischman et al. More detailed descriptions of other energyemitting ablation elements which may be suitable according to thepresent invention are disclosed in U.S. Pat. No. 4,641,649 to Walinskyet al. (microwave ablation); and U.S. Pat. No. 5,156,157 to Valenta, Jr.et al. (laser ablation). The disclosures of these patents are hereinincorporated in their entirety by reference thereto.

In addition, other elements for altering the nature of tissue may besuitable as “ablation elements” within the intended meaning of thecurrent invention. For example, a cryoblation probe element adapted tosufficiently cool tissue to substantially alter the structure thereofmay be suitable. Furthermore, a fluid delivery element, such as adiscrete port or a plurality of ports which are fluidly coupled to afluid delivery source, may be adapted to infuse an ablating fluid, suchas a fluid containing alcohol, into the tissue adjacent to the port orports to substantially alter the nature of that tissue. More detailedexamples of cryoblation or fluid delivery elements such as those justdescribed are disclosed in U.S. Pat. No. 5,147,355 to Friedman et al.and WO 95/19738 to Milder, respectively. The disclosures of thesepatents are incorporated in their entirety by reference thereto.

It is also to be further appreciated that the various embodiments shownand described in this disclosure collectively provide one beneficialmode of the invention, which mode is specifically adapted for use in theleft atrium of a mammal. In this mode, the elongate ablation element isadapted to have its ends anchored in adjacent pulmonary vein ostia inthe left atrium, with the elongate ablation element in substantialcontact with the tissue that spans the length between those ostia. Bysubsequent ablation of the tissue between anchors in the adjacent ostia,a long linear lesion is created and provides a conduction block toelectrical flow across the length of the lesion.

As will be appreciated from the more detailed disclosure of theembodiments below, a pattern of multiple long linear lesions betweenadjacent pulmonary vein ostia, and also including portions of the mitralvalve annulus and septum, may be completed with the present invention.One pattern of such multiple ablation lesions can be considered a “box”of isolated conduction within the region of the pulmonary veins, and isbelieved to provide a less-invasive improvement and less traumaticalternative to the invasive “maze” surgical procedure previouslydescribed.

FIG. 1 shows one variation of the present invention wherein a tissueablation device assembly (1) is shown to include an ablation catheter(2) which has an elongate body (10) with a proximal end portion (11) anda distal end portion (12). Distal end portion (12) is shown to includean ablation element (20) which is bordered on each of two ends (23,24)by distal and intermediate guidewire tracking members (30,40),respectively.

The anchors of the variation shown in FIG. 1 are provided by the distaland intermediate guidewire tracking members (30,40). These guidewiretracking members are generally shown in FIG. 1 to be slideably engagedover distal and proximal guidewires (3,4), respectively, to form a“multi-rail” catheter system. Guidewire (3) is further shown to includea stop (13) that is radially enlarged with a diameter which is largerthan the diameter of the first distal guidewire port (32). The stop (13)provides one positioning means for placing the distal guidewire trackingmember (30) at a predetermined location along the guidewire to anchor itin that position in the anatomy, as will be more readily apparent byreference to FIG. 3 below. In addition to the use of the stop mechanismshown, other structures may be employed to provide relative positioningof the catheter over the guidewire, such as by use of an expandablemember on the guidewire to internally engage the guidewire trackinglumen, as would be apparent to one of ordinary skill.

Ablation element (20) is shown in the variation of FIG. 1 to include aplurality of electrodes (25) which are variously positioned along thelength of the elongate body (10). A second ablation element (50) is alsoshown to include a second plurality of electrodes (55). As will bedeveloped in more detail with regard to FIGS. 11-15B below, theelectrodes of these ablation elements are adapted via electrode leads toat least one ablation actuator and also to instruments which are adaptedto monitor intercardiac electrical signals and to artificially pacecardiac contractile rhythm via the electrodes. In the variation shown, acommon bundle of electrode leads (26) couple the various electrodes tothe proximal coupler (60).

In general, any of several designs for coupler (60) may be suitable foruse with the present invention, as would be apparent to one of ordinaryskill. In the variation shown in FIG. 1, proximal coupler (60) engagesproximal end portion (11) of the elongate body (10) of ablation catheter(2). Proximal coupler (60) includes a hemostatic valve (61) which isshown to slideably engage and provide fluid integrity around stylet (5).An electrical coupler (62) is also included, which is schematicallyshown selectively coupled to ablation actuator (90), signal recordingdevice (91), and pacing device (93). Still further, a hydraulic coupler(68) is also shown and is fluidly coupled to fluid ports (28) forpurposes of suction or fluid delivery.

Ablation actuator (90) is engaged to both electrical coupler (62) andalso to a ground patch (98). A circuit is thereby created which includesthe ablation actuator (90), the ablation element (20), the patient'sbody (not shown), and the ground patch (98) which provides either earthground or floating ground to the current source. In this circuit, anelectrical current, such as a radiofrequency (“RF”) signal may be sentthrough the patient between the electrode element and the ground patch,as would be apparent to one of ordinary skill.

Ablation Element Anchors

Further detail regarding the anchors shown at distal and proximalguidewire tracking members (30,40) in FIG. 1 is provided as follows.Distal guidewire tracking member (30) includes a distal lumen (notshown) which extends between a first distal guidewire port (32) in thecatheter tip and a second distal guidewire port (34) located proximallyof the first distal guidewire port. Intermediate guidewire trackingmember (40) is positioned on an intermediate portion of the elongatebody of the catheter and includes an intermediate lumen (not shown)which extends between a first intermediate guidewire port (42) and asecond intermediate guidewire port (44) located proximally of the firstintermediate guidewire port.

Therefore, each of the guidewire tracking members (30,40) shown in FIG.1 is adapted to receive the respective guidewire through its lumen suchthat the guidewire extends externally of the catheter's elongate body oneither side of the region of slideable engagement. This arrangement,however, is merely one example of a broader functional structure of theguidewire tracking variation illustrated by the anchors of FIG. 1.Considering this variation more generally, bores are formed at each ofthe distal and intermediate regions of the elongate body. Each bore isadapted to track over a guidewire separately and independently of theother bore. Each bore generally has two open ends or ports, and therespectively engaged guidewire extends through the bore and externallyof the device from each bore end.

Therefore, according to the general structure just described, thespecific guidewire tracking member embodiments of FIG. 1 may be modifiedaccording to one of ordinary skill without departing from the scope ofthe invention. For example, a cuff or looped tether of material may beprovided at the desired anchoring location along the elongate body andthereby form a bore that is adapted to circumferentially engage aguidewire according to the description above. More particularly, ametallic ring, or a polymeric ring such as polyimide, polyethylene,polyvinyl chloride, fluoroethylpolymer (FEP), or polytetrafluoroethylene(PTFE) may extend from the elongate body in a sufficient variation. Or,a suitable strand of material for forming a looped bore for guidewireengagement may also be constructed out of a filament fiber, such as aKevlar or nylon filament fiber. One more specific example of such analternative guidewire tracking member which may be suitable for use inthe current invention, particularly as a distal guidewire trackingmember, is disclosed in U.S. Pat. No. 5,505,702 to Arney. The disclosureof that reference is herein incorporated in its entirety by referencethereto.

Further to the intermediate guidewire tracking member (40) of FIG. 1, ameans is beneficially provided by that member for positioning andanchoring an intermediate region of an elongate catheter body at apredetermined location within a body space. The embodiment shown in FIG.1 allows the engaged guidewire to traverse the radial axis of theelongate body, entering on one side of the catheter and exiting on theother. This embodiment may be constructed in a variety of ways,including, for example, the more specific embodiments providedcollectively in FIGS. 2A-E.

FIGS. 2C-D show an outer tubing (41) which coaxially surrounds an innerguidewire tubing (43). Guidewire tubing (43) is adhered to either sideof the internal wall of the outer tubing (41). In one method, this maybe accomplished by extending a shaped metallic mandrel within theinterior lumen of the guidewire tubing (43) which forces that tubingagainst the wall of the outer tubing at preferred locations where portsare desired. By subsequently heating the region or regions of contact,such as by induction heating of the mandrel, the guidewire and outertubings may melt together. This melt bond procedure may be performedsimultaneously at each tubing interface or in series. After melting thetubings together and subsequent cooling, the mandrel is withdrawn.

Apertures are formed at the melted tubing interfaces such as by laser ormechanical drilling (either before or after withdrawal of the mandrel).Optionally, the ends of the inner tubing on the outer border of eachformed port may be blocked, such as by filling the cross section oftubing in that region with adhesive or further melting a plug of similarmaterial in that region (45), as would be apparent to one of ordinaryskill.

The structure shown in FIGS. 2C-D allows for the required guidewiretracking lumen and also maintains at least one additional, longitudinalconduit through the region of the guidewire tracking lumen between theguidewire tubing (43) and the outer tubing (41). This allows for thepassage of electrode leads (26), and may also provide for additionalelements to communicate therethrough, such as for slideably advancingstylets therethrough or for suction/fluid delivery, as will be discussedin more detail below.

FIG. 2E shows a further embodiment for intermediate guidewire trackingmember (40), wherein a multi-lumen extruded tubing (41′) includes acentral lumen as the guidewire lumen (43′). Guidewire lumen (43′) isbordered on either side by a first lumen, shown as electrode lead lumen(46), and a second lumen (47) which has varied additional functionalityas just described for FIGS. 2C-D, including suctioning, fluid delivery,and passage of stylets for remote manipulation of distal catheterregions. In this embodiment, first and second intermediate guidewireports (42,44) may be formed at the same longitudinal position along theelongate catheter body, rather than in staggered proximal-distalarrangement. In this design, a guidewire may slideably engage thetracking member in a perpendicular plane to the longitudinal axis of theelongate body.

FIG. 3 further shows tissue ablation device assembly (1) in use duringthe formation of a long linear lesion between adjacent pulmonary veinostia in a left atrium (80). In this Figure (and further regarding thealternative variations shown in FIGS. 4-9) the ablation catheter (2) isshown with the distal and intermediate guidewire tracking members(30,40) in the left and right superior pulmonary vein ostia (83,84),respectively. This particular arrangement is provided merely for thepurpose of illustrating the operation of the anchoring mechanisms whichare beneficially provided with the long linear lesioning device of thecurrent invention. The proximal end portion (11) of the elongate body isfurther shown throughout FIGS. 3-9C in schematic view in order toillustrate engagement of the ablation element to ablation actuator (90),which is further schematically shown coupled to a return electrode (98),and also to signal recording device (91) and pacing device (93).

FIG. 3 initially shows two guidewires (3,4) which have been previouslyplaced within the left and right pulmonary veins through theircorresponding ostia (83,84) via transeptal sheath (6). This guidewirepositioning may be accomplished by virtue of the steerability andresultant sub-selectability of the guidewires, themselves, within theatrial chamber. In addition or in the alternative, enhanced guidingsystems such as that disclosed in U.S. Pat. No. 5,575,766 to Swartz etal. may also be used to enhance the positioning of each guidewire intothe desired vein ostia.

Suitable guidewires for use in the present invention may vary, andpreviously known guidewire designs for placing other catheter deviceassemblies within the internal body spaces of the anatomy may besuitable for many applications. In general, these guidewires have ametallic core, such as a stainless steel core or a superelastic metalliccore, including a nickel-titanium core, which tapers distally andincludes a radiopaque coil soldered, welded, or brazed over the taperedregion.

Furthermore, commonly known guidewires having an outer diameter of atleast 0.014″, including those having an outer diameter of approximately0.018″ or 0.032″, may be suitable. The guidewires should also be eitherpre-shaped or shapeable in their distal tip region, and should also betorqueable and radiopaque (such as by the radiopaque coils justdescribed), such that the device may be manipulated to sub-select thepulmonary vein ostia in the atrium under Xray fluoroscopy. In any event,the guidewires should be of suitable construction in order to providesufficient support and steerability to position and guide the catheterassembly of the present invention into the pulmonary vein ostia withinthe atrium, as would be apparent to one of ordinary skill.

Stop (13) is a radial enlargement which may be formed as a separatemember over the underlying guidewire construction. Stop (13) may be madefor example by soldering a ball of solder onto the outer surface of theunderlying wire. Stop (13) may also be a polymeric member, such as thatchosen from the group of polymers consisting of polyethylene,polyurethane, polyvinyl chloride, or the like. Furthermore, an enlargedregion of adhesive such as a cyanoacrylate adhesive may be formed overthe guidewire to form the stop (13).

Once placed in the respective ostia, each of the guidewires (3,4)provides an initial platform over which a region of the ablationcatheter assembly engaged with the guidewire may be positioned foranchoring at the respective vein ostia. FIG. 3 shows the distal endportion of ablation catheter (2) after it has been advanced in abeneficial arrangement over the two guidewires (3,4). Each of the distaland intermediate guidewire tracking members (30,40) is coaxially engagedover guidewires (3,4), respectively, according to the followingexemplary procedure.

After the guidewire distal end portions are positioned in vivo asdescribed, the guidewire proximal end portions (not shown) may be“backloaded” into the respective distal and intermediate guidewirelumens of the catheter assembly. This is done by inserting the guidewireproximal end into for example the first distal guidewire port (32), andthen retrogradedly advancing that guidewire proximal end rearwardlythrough the distal lumen and out the second distal guidewire port (34).

Once the guidewires (3,4) and guidewire tracking members (30,40) arerespectively engaged, the ablation catheter (2) is advanced over theguidewires (3,4) and into the region of their respective distal endportions in the internal body space. The distal end portion of ablationcatheter (2) is advanced with respect to guidewire (3) until firstdistal guidewire port (32) confronts stop (13) within the firstpulmonary vein, as shown in FIG. 3. With stop (13) positioned in apredetermined location along pulmonary vein with respect to ostium (83),the confronting engagement with distal guidewire tracking member (30)selectively positions the distal end (23) of the ablation element at adesired location within the ostium.

Second distal guidewire port (34) is actually shown in FIG. 3 to belocated within the distal region of ablation element (20), and ispositioned in the space between adjacent ablation electrodes. In thisarrangement, the region of coaxial coupling between guidewire (3) andthe second distal guidewire port (34) may be positioned at or proximalto the pulmonary vein ostium, while a portion of the ablation element(20) may still be positioned within the ostium. It is believed that, forthe purposes of forming efficacious conduction blocks in the regions ofthe left atrial pulmonary vein ostia, the long linear lesions shouldextend between and include at least the base of the pulmonary veinsadjacent the ostia.

In addition to anchoring distal end (23) of the ablation element (20) ina first pulmonary vein ostium (83) as just described, proximal end (24)is anchored in the region of the adjacent right superior pulmonary veinostium (84) by coaxially advancing intermediate guidewire trackingmember (40) over guidewire (4).

Subsequent to positioning and anchoring each of the ends of ablationelement (20), the ablation element is thereby adapted at least in partto substantially and firmly contact the length of tissue between theablation element ends, including a linear region of tissue between theostia and also portions of the ostia and veins stemming therefrom (atleast at the first ostia). By energizing the electrodes along theanchored ablation element, the adjacent tissue is ablated to form a longlinear lesion between the predetermined anchoring locations at theostia.

It may also be desirable according to this invention to position a thirdportion of the device at a third predetermined location along the bodyspace wall. For example, a second ablation element (50) is shownvariously throughout the figures to be positioned on the ablationcatheter (2) proximally of the ablation element (20). Second ablationelement (50) has its distal end anchored in the vicinity of the secondpredetermined anchoring location within the right superior pulmonaryvein ostia via intermediate guidewire tracking member (40).

A third anchoring or positioning means may be provided in order toposition the proximal end of the second ablation element (50) at thethird predetermined location to allow for another long linear lesion tobe formed in a predetermined orientation and pattern along the atrialwall relative to the first lesion formed by the first ablation element.For example, stylet (5) is adapted to function in this positioning roleand is shown in shadowed view variously throughout the figures withinthe region of the second ablation element (50). The stylet (5) isengaged within a stylet lumen (not shown) within the elongate body andis adapted to remotely manipulate the positioning of the ablationcatheter (2) at the third location.

The construction of the stylet used in the various embodiments of theinvention may vary, and is determined by the particular performanceneeds of a specific application. A suitable stylet may be a metalmandrel, such as a stainless steel mandrel or a superelastic metallicmandrel (for example, a nickel-titanium mandrel), which is slideablyadvanceable within a proximal lumen of the ablation catheter. The styletmay also be coated with a lubricious coating, such as with afluoroethylpolymer (FEP), polytetrafluoroethylene (PTFE), paralene, or ahydrophilic polymeric coating, in order to facilitate slideablemanipulation of the stylet within the stylet lumen of the elongate body.

Further, the stylet should generally have a length adapted such that thedistal end may be placed at the required region of the ablation catheterfor in vivo positioning while the stylet proximal end extends externallyof the body and the assembly to allow for remote manipulation by aphysician user at its proximal extremity. Still further, the styletshould be preshaped in its distal end region, such that torsion on theproximal extremity of the stylet is adapted to controllably andtranslumenally manipulate the stylet tip in order to position thecoaxially engaged catheter shaft along the atrial wall surface.

Further to the beneficial “catheter manipulating” role of the styletjust described, only one anchor may be necessary in some circumstancesto achieve firm contact with a body space wall along the length of anelongate ablation element. By anchoring one end of the ablation elementat a first predetermined location, such as in a pulmonary vein ostia,the shaped stylet may be used to position the other end or portion at asecond predetermined location. In this manner, the first anchor providesa focus about which the stylet's manipulation may sweep the otherportion of the ablation element, much like a compass may be used tosweep an arc or position a point about that arc at a predeterminedlocation relative to the first location of the focus.

Stylet (5) may also be adapted to advance further distally within thecatheter, particularly during in vivo placement and anchoring of thedistal guidewire tracking member at the first anchoring location. In oneparticular variation, the region of the elongate body which houses theablation element may be designed to be particularly flexible, such asfor the purpose of conforming to the atrial wall anatomy. Thisflexibility may, however, sacrifice pushability and the ability toadvance and remotely manipulate the distal end portion within the bodyspace. Therefore, the variable positioning and use of the stylet withinthis distal catheter region may allow for the requisite stiffness totrack, position, and anchor the ablation element when the stylet isadvanced within that region, and allow also for flexible conformity ofthe ablation element to the atrial wall when the stylet is proximallywithdrawn.

As would be apparent to one of ordinary skill, stylet (5) is also shownin shadowed view variously throughout the rest of the figures and isintended to perform similar functions in the variations of those figuresas those just described.

Further to the “third location” positioning feature just described, athird anchor may also be provided on the device, such as proximally ofthe second ablation element (50) shown in FIGS. 1 and 3. For example, a“proximal guidewire tracking member” (not shown) similar to theintermediate guidewire tracking member embodiments described may beprovided as a third anchor adjacent to the proximal end of the secondablation element. By engaging that third anchor to an additionalguidewire, for example, the proximal guidewire tracking region may bepositioned and anchored over the additional guidewire in yet a thirdostium, such as the right inferior pulmonary vein ostium according tothe device positioning shown in FIG. 3.

As would be apparent to one of ordinary skill, additional anchors and/orablation elements may also be provided along the elongate body incombination with those just described. For example, additional proximalguidewire tracking members may be provided, or additional stylets mayslideably engage the interior lumens of the device elongate body, forthe purpose of positioning other proximal portions of the elongate bodywithin the anatomy.

In one particular mode not shown, a plurality of ablation elements maybe positioned between all adjacent pairs of vein ostia by use of adesirably positioned plurality of anchors along the elongate body whichare adapted to simultaneously engage the regions of those individualostia. Preferable to this mode, however, the region between the inferiorvein ostia need not be ablated or engaged with an anchored ablationelement. This is because it is believed that a complete “box” pattern ofconduction block which would otherwise result may create one or more newreentrant arrhythmia wavelets through the atrial wall tissue surroundingthat box. Instead, it is believed preferable in many cases to createlesions which bridge these inferior ostia to the anatomical barrier ofthe mitral valve annulus.

Thus, stylet (5) or a proximal guidewire tracking member as previouslydescribed may be used to position a proximal end of an ablation element,such as second ablation element (50) shown in FIG. 3, in the vicinity ofthe mitral valve annulus. In the case of a proximal guidewire trackingmember in this application, a guidewire engaged with that member isplaced anterograde from the atrium and into the ventricle through themitral valve. The proximal guidewire tracking member is then advancedover the wire until positioned at the desired location along the mitralvalve annulus. In either the stylet or guidewire tracking membervariation, a long linear lesion may be thus formed between theanatomical structure of the superior or inferior vein ostia and themitral valve annulus.

FIG. 4 shows a further variation of the use of stop members on theengaged guidewires through the distal and intermediate guidewiretracking members of the current invention. In this variation, guidewire(4′) includes a stop (14) which is positioned proximally of the secondintermediate guidewire port (44). In this arrangement, the wire distalend portion is preferably “front-loaded” into the intermediate guidewiretracking member prior to introducing the wire into the body. This isbecause only such front-loading would result in the arrangement shown(“back-loading” of the guidewire would not be possible because the stopwould block the tracking member from being positioned distallythereover). In this arrangement, guidewire (4′) may be used to push theproximal end (24) of the ablation element (20) distally against theengaged pulmonary vein ostia in order to more firmly anchor the proximalend (24) into that ostium.

In addition to preferred shaped distal tips for the guidewires suitablein this variation, a guidewire region which includes or is locatedproximal of the stop may also have a shape in order to enhance this“pushing” function of the proximal stop variation. For example, asweeping or discrete bend in the wire proximally of the stop may enhancedirecting the vector of force along the wire's length transversely fromthe wire's entrance into the left atrium through the guiding catheter inthe fossa ovalis and toward the posterior atrial wall in the region ofthe pulmonary vein ostia.

FIG. 5 shows still a further variation incorporating the use of stopmembers on the guidewires to provide a means for forcing the engagedregion of the ablation catheter against the tissue adjacent the veinostia. In this variation, both guidewires (3,4′) have stop members(13′,14), respectively, which are positioned proximally of therespectively engaged distal and intermediate guidewire tracking members(30,40). According to the prior description by reference to FIG. 4, thisassembly must be entirely “pre-loaded” with the distal ends of theguidewires inserted into the respective lumens of the respectivetracking members. The assembly of this variation benefits from theability to have force applied distally toward the desired anchoringlocations in the adjacent pulmonary vein ostia via the proximallypositioned stops on the guidewires.

FIG. 6 show still a further variation of the ablation element anchoringfeature of the current invention, wherein the distal end (23) ofablation element (20) is bordered by an expandable element (35) which isadapted to radially engage at least two opposite portions of thepulmonary vein wall within which the expandable element is positioned.

In this variation, the guidewire tracking methods for positioning thevarious regions of the ablation catheter relative to the pulmonary veinostia may be substantially the same as for the previously described“guidewire stop” variations. However, once positioned, the device may bemore substantially secured in that position due to the radial expansionof the expandable element.

In one mode, expandable element (35) is an inflatable balloon which ishydraulically coupled to a pressurizeable fluid source. Uponpressurization of the fluid source, fluid is forced into the balloon tohydraulically expand its diameter at least until circumferentiallyengaging a portion of the vein wall. In this mode, regions of theablation catheter proximal to the balloon must provide a hydraulic fluidconduit such as an isolated inflation lumen that is coupled both to theballoon and also to the pressurizeable inflation source through theproximal coupler, as would be apparent to one of ordinary skill.Preferably, the inflation source includes a source of radiopaque fluidwhich is adapted for visualizing inflation characteristics of theballoon upon X-ray fluoroscopy.

One suitable mode of construction for expandable element (35) as aninflatable balloon is as follows. The balloon may be a relativelyelastic, expandable tubing, such as a latex rubber or silicone tubing,or may be a relatively less compliant, folded balloon, such as apolyethylene, polyolefin copolymer, polyvinyl chloride, or nylonballoon, which has relatively slight, controlled compliance duringpressurization. In the case of an elastically constructed balloon, theballoon may have predetermined sizing based substantially upon volume offluid used to inflate the balloon. In the less compliant construction, akit of ablation catheters with several predetermined sizes over a rangeof operating pressures may be provided in order to accommodate varyingpulmonary vein anatomies and diameters.

In other modes of this variation, expandable element (35) may beradially expandable in ways other than hydraulic inflation of a balloon.For example, a radially expandable cage may provide enough radial forceon the vein wall to provide a sufficient anchor to that region of theablation assembly. Other expandable members may also be suitable, suchas those described in U.S. Pat. No. 5,509,900 to Kirkman, which isherein incorporated in its entirety by reference thereto.

Further to the modes described and obvious variations thereof,expandable element (35) may also be adapted to preferentially expand inone radial direction versus another, such that the central axis of theunderlying elongate body is biased to one side of the expanded element'sdiameter. This may for example be particularly desirable for forcing themost distal electrodes of the ablation element, which are adjacent theexpandable element, against a particular portion of the pulmonary veinwall. Without such radial bias, it is believed that a lack of intimalwall contact may result in regions of the elongate body adjacent to theexpandable element. Preferably, the bias forces the adjacent region ofthe ablation element against the interior wall of the vessel which isbetween the anchors, thereby resulting in a long continuous lesion thatextends with continuity up into the engaged vein.

FIG. 7 shows a further variation of the intermediate guidewire trackingmember (40) which forms the anchor adjacent the proximal end (24) of theablation element (20). In contrast to the previously describedvariations, the intermediate guidewire tracking member (40) includes anintermediate lumen which has a second intermediate guidewire port (notshown) which is located at or near the proximal end portions of theablation catheter (2), such as at the proximal coupler (not shown). Itis believed that this elongated coaxial arrangement of at least one ofthe guidewire tracking members may provide a benefit in reducing thenumber of devices which are exposed to the internal bores of thedelivery device and also within the atrium. Similarly, the need toinclude means for the intermediate guidewire to traverse the diameter ofthe elongate body as described by reference to FIGS. 2A-E above isremoved by this variation.

Building upon the variation shown and described with reference to FIG.7, FIG. 8 shows the distal end portion of ablation catheter (2) to bebranched such that intermediate guidewire tracking member (40) includesan intermediate leg (47). In this variation, the intermediate leg (47)provides a platform upon which additional electrodes (26) may bepositioned to allow the proximal end of ablation element (20) to extendfurther into the second pulmonary vein ostium in which the intermediateguidewire tracking member (40) is anchored.

Intermediate leg (47) may be constructed according to a variety ofmethods. In one method, a first polymeric tubing includes proximal shaft(11) and has a port formed through its outer wall and into a lumenformed by that tubing. A second tubing of similar material is placedsnugly over a mandrel, such as a teflon coated stainless steel mandrel,which mandrel is inserted into the lumen through the port until the endof the second tubing circumferentially engages the port. Preferably inthis method the port and the engaging end of the second tubing (which isactually a second port) are adapted with predetermined geometriessufficient to mate their orifices to form a substantial seal at theirinterface. The engaged region of tubings is next placed next to aninductive heating source which is energized to sufficiently heat theadjacent region of mandrel in order to melt the region of the secondtubing and thereby splice the tubings together in that region.

After heating as described, the mandrel is removed. In addition to thetwo-tubing adaption just described, an additional step may be toheatshrink a third piece of tubing over the two-tubing adaption prior toremoval of the mandrel in order to provide some additional structuralintegrity to the adaption. In this method, the second tubing may beeither the intermediate leg (47) or the distal end portion of theablation catheter (2).

An additional method of forming the branched intermediate and distal endportions of the ablation catheter of the current invention may be asfollows. An extruded polymeric tubing having two round lumens separatedby a central wall, or a “dual lumen” extrusion, is cut to apredetermined length. One end of the dual lumen extrusion is cut alongthe tubing's longitudinal axis through the central wall to create thebifurcation.

The resulting branched tubings in this alternative method may then be“post-processed” to prepare the tubings for adapting the electrodeelements along their length, as would be apparent to one of ordinaryskill. For example, the flat surfaces created by the formation of thebranched tubings just described may be rounded such as by grinding or bymelting the tubing within pieces of coaxial heat shrink tubing whilemandrels are placed within the tubings (the heat shrink tubing of thisvariation would be removed after heat shrinking, and would be adissimilar material such as a teflon heat shrink tubing or a polyimideheatshrink tubing).

In a further alternative, the resulting flat surfaces of the branchedtubings may be desired, particularly since these surface would benaturally oriented to confront the tissue within and between thepulmonary vein ostia. The ablation element such as a plurality ofelectrode sub-elements may be placed only onto the flat surfaces createdand would thus be substantially isolated to the elongate region oftissue contact along the length of the ablation element.

FIGS. 9A-C collectively portray a further variation of the distalguidewire tracking member as an anchoring means, which is shown incombination with the intermediate guidewire tracking member variationshown initially in FIG. 7. In this variation, neither of the guidewiretracking members has a second guidewire port located proximally of thefirst relative guidewire port in the region of the distal end portion ofthe ablation catheter. Rather, each of the distal and intermediatelumens extends proximally along the length of the elongate body of thecatheter and terminates in a port (not shown) on the proximal endportion (11) of the catheter. Further to this variation, a stop may beprovided on the guidewire engaged within the distal lumen of the distalguidewire tracking member, such as shown at stop (13′) on guidewire (3)in FIG. 9A

FIGS. 9B-C however show a different anchoring emodiment in the distalanchor than that shown in FIG. 9A. Rather than the use of a stop memberon the guidewire (which could also be combined with the FIG. 9B-Cvariation), the FIG. 9B-C variation combines the catheter-guidewiretracking design of FIG. 9A with an expandable member anchoring mechanismat the distal device end, such as that shown previously in FIG. 6. Stilldifferent from the FIG. 6 varation for expandable element (35), thevariation of FIGS. 9B-C allows for the guidewire (3) to be withdrawnproximally from the portion of the guidewire lumen which extends betweenthe first distal guidewire port (33) and the second distal guidewireport (34). Therefore, according to the mode of operation shown in FIG.9C, when the guidewire (3) is so withdrawn during expansion of theexpandable element, blood flow is allowed to perfuse proximally throughthe open region of guidewire lumen and into the atrium (shown in boldedarrows). Without the guidewire and port arrangement provided in thisvariation, the expanded balloon in the variation shown would otherwisefunctionally occludes such flow. Furthermore, while the variation ofFIG. 6 could functionally be used in the same manner by withdrawing wire(3) from the engaged lumen, wire engagement would be lost and would besubstantially unrecoverable according to that design when used in remotebody spaces such as in percutaneous procedures in the atrial chambers.

The present invention has been heretofore shown and described byreference to particular variations of anchors at distal and intermediatecatheter regions adjacent to two opposite ends of an ablation element,respectively. These anchoring variations are adapted to allow forsubstantial tissue contact between the ablation element ends forcreating a continuous, long linear lesion. However, it is furthercontemplated that the region of the ablation element itself may beadditionally adapted to increase tissue contact along its length betweenthe anchors at adjacent pulmonary vein ostia.

For example, the ablation element may include at least one ablationelement anchor along its length which is adapted to engage the tissueadjacent to the element. In one particular embodiment, the ablationelement anchor may be a suctioning means which includes at least oneport in fluid communication with a vacuum source via a suction/air lumenextending through the body of the ablation catheter. An example of thisembodiment is shown in overview fashion in FIG. 1, wherein further moredetailed examples are provided in FIGS. 10A-F.

FIGS. 10A-E show various levels of detail of a similar ablation cathetervariation as that shown in FIG. 7 for purpose of illustration, and showa more detailed mode which includes a suctioning anchor means in theregion of the ablation element (120). The ablation element (120)includes a portion of a fluid lumen (127) which communicates exteriorlyof the catheter device in the region of the ablation element through aplurality of fluid ports (128). These ports are positioned such thatthey face the tissue adjacent to the ablation element when the distaland intermediate guidewire tracking members (130,140) are anchored inadjacent pulmonary vein ostia. Fluid lumen (127) is adapted to couple toa vacuum source via a proximal coupler (not shown), in order to providea suction force at the fluid ports (128) during ablation such that theablation element is firmly in tissue contact during the ablation.Further included in this variation and shown in shadow in FIG. 10A andin cross section in FIG. 10E is an internal seal (129).

Seal (129) is located internally of fluid lumen (127) and distallytherein relative to the most distal of fluid ports (128). This seal(129) provides one means for allowing for fluid isolation between thesuction lumen in the region of the ablation element and the guidewiretracking member and its corresponding lumen. Various methods may be usedfor creating the seal (129), such as for example delivering a bolus ofhigh viscosity or quick curing adhesive to the desired interlumenallocation for the seal, or for example, by melting a plug of materialwithin that lumen, or a combination of these or other methods.

Other means may also be used for enhancing tissue contact along thelength of the ablation element in the alternative or in addition to thesuctioning means just described. For example, the region of the cathetercontaining the ablation element, particularly between the ablationelement's ends, may also be preshaped in a manner such that the ablationelement has a bias into the tissue between the predetermined locationsat which the ablation element ends are anchored. This bias may be heatset into the polymeric tubing making up the elongate body in the regionof the ablation element, or may otherwise be formed, such as for exampleby providing a pre-shaped reinforcing member at that region of theelongate body. Such a pre-shape may be provided, as a further example,by means of the stylet (5) shown variously throughout the figures. Inthis mode, the stylet is adapted to advance distally into the region ofthe ablation element an to impart a biased shape to that region.

Both the suctioning means described, as well as the preshaped biasmeans, are designed to take advantage of a natural orienting feature ofan ablation catheter according to the anchoring mechanisms of thepresent invention. When the anchors used in a particular variation areguidewire tracking members adapted to anchor in adjacent vessel ostia,such as in the variations heretofore described, the two guidewiretracking members will generally tend to take a natural, predictableorientation along the engaged guidewire axis. The ablation elementextending between those oriented anchors will also generally tend toorient in a predictable fashion when engaged to the tissue in order toaccommodate the preshaped bias variation and the fluid port/suctionvariations just described for the ablation element of the currentinvention.

FIG. 10F shows a further variation of the device assembly shown in FIGS.10A-E, wherein the ablation element (220) has been modified. An energysink (270) is provided in this variation which, rather than beingdisposed in a fixed orientation on the external surface of the elongatebody, is instead slideably engaged within a lumen (not shown) incommunication with the plurality of fluid ports (228). The energy sink(270) may be any of the alternative energy sources or other ablationtechnologies introduced above, such as an RF electrode, microwaveantenna, cryoblation probe, fiber optic laser source, or ultrasoundsource. Preferably, however, the ablation means of this variation isadapted to ablate through the ports as it is moved to traverse acrossthose ports while actuated for ablation.

It is further contemplated that the plurality of ports shown in FIGS.10A-E might be engaged to mechanical, tissue engaging tools via coupledlumens within the interior regions of the device. In one mode, each of aplurality of ports is slideably engaged to a needle which is adapted toadvance through the port and into the adjacent tissue as an anchor.

Ablation Element

The particular geometry and dimensions of the electrodes along thelength of the ablation element (20) may effect the overall ablationcharacteristics, and a variety of arrangements may be suited forparticular applications without departing from the scope of the presentinvention. However, these electrodes generally may be made ofelectrically conducting material, such as copper alloy, platinum, orgold, and may be wrapped about the flexible body of the device.Furthermore, in order to effectuate efficient ablation the electrodesshould generally be designed to provide a suitable contact area with thetissue wall adjacent to the ablation element when anchored in place.

Still further, where a plurality of spaced electrodes are used such asin the variation of FIG. 1, the length and spacing of the electrodes maybe particularly adapted to accommodate the ablation energy to be used.This combination is desired in order to optimize the creation of acontinuous, long linear pattern of ablation which includes the regionsbetween the electrodes. For example, particularly in the case ofcreating long linear lesions in atrial wall tissue, it is believed thatgaps in such lesions may provide a route for reentrant atrial arrhythmiawhich might otherwise be blocked with a suitably contiguous lesion.Furthermore, it is believed that the desired lesions should betransmural, or from one side of the atrial wall to the other, in orderto effectively block aberrant reentrant signals from bridging across thelesion and resulting in arrhythmia.

One electrode construction which is believed to be particularly wellsuited for use in ablating long linear lesions in the left atrial wallis as follows. A plurality of electrodes is provided along the ablationelement, each electrode being constructed of a circumferentially coiledmetallic wire, preferably a platinum wire. Each coiled electrode has awidth that preferably ranges from 5 to 8 millimeters, and each adjacentpair of electrodes is preferably spaced 1 to 2 centimeters apart. It isbelieved that simultaneously energizing a plurality of electrodesaccording to this construction at a frequency of 500 KHz and at a powerlevel ranging from 50-100 W will form a long linear lesion in atrialwall tissue sufficient to form a conduction block in many cases. Thenumber of electrodes positioned along the ablation element according tothese parameters may vary depending upon the overall desired ablationelement length in order to form a particular long linear lesion.

An initial overview of one electrical coupling arrangement for theablation element of the current invention was provided by reference toFIGS. 1 and 3-9C. Further to the variations of those figures, signalrecording device (91) may be coupled to the electrodes of the ablationelement for the purpose of monitoring for arrhytmias prior to, during,or after ablation is performed with those same electrodes, as would beapparent to one of ordinary skill. This recording device is preferrablyused after anchoring the ablation element at the desired region forforming the desired long linear lesion. Such recording of atrialelectrograms alows a treating physician to: (1) confirm arrhythmia inthe region of anchored ablation element; (2) define the anatomicallimits of the atrial tissue along the ablation element length (whenmonitored at each electrode, such as extending outwardly along the wallof the pulmonary veins); (3) to assess the closeness of the ablationelement to the mitral valve annulus (both atrial and ventricularelectrical signals appear at the respective leads when at the annulus);and (4) to monitor conduction block after performing an ablation. It isbelieved that, by adequately securing and anchoring the ablation elementto the ablation region before, during, and after ablation, accuraterecording and subsequent analysis of the treatment may be achieved in abeating heart.

In more detail, one example of a suitable recording device for use withthe present invention is the “CardioLab”™ system by Pruka EngineeringIncorporated (“PEI”), located in Houston, Tex.

Further to the understanding of pacing device (93) shown variouslythroughout the previous figures, that device selectively allowsartificial stimulation to the region of ablation in order to assess theconduction block ideally formed. In one mode, the ablated tissue ispreferrably dead and non-conductive and actuating the electrodes alongthat region via a pacing rhythm should not result in significant atrialwall conduction or wall motion response. Furthermore, by shifting theablation element off-axis of the ablation region, pacing may be achievedand conduction block of a known signal may be assessed. One example of asuitable pacing device for use with the present invention is theprogrammed pacing stimulator made by Bloom, Inc. In one exemplary modeof operation, 1-20 mA of current in a square wave with a pulse width of1 to 10 msec may be sufficient to induce arrhythmias to monitor theregion of conduction block, or to pace map, or to measure pacingthreshold of the targetted tissue pre- or post-ablation.

For purposes of providing a more thorough understanding of the structureof the ablation element, itsels, FIGS. 11-14 provide more detailed viewsof variations for the ablation element as it is positioned on theablation catheter.

FIG. 11 shows a plurality of electrodes (25) which are coupled toelectrode leads (26), respectively, which are shown to extend proximallyalong the length of the catheter elongate body (10) where they are thenengaged to at least one electrical coupler (not shown).

Ablation element (20) may also include temperature monitoring elements,as are also shown in FIG. 11 at thermistors (27). The inclusion of thesethermistors (which may also be thermocouples) provide a means formeasuring the temperature in the region of the ablation element forpurposes of feedback control during the ablation procedure. Each ofthermistors (27) is shown in FIG. 11 to be positioned in the vicinity ofone of the electrodes (25) and is also coupled to one of temperaturemonitoring leads (29). A further variant of the embodiment shown in FIG.11 is provided in FIGS. 12 and 13, wherein thermocouples (27′), insteadof thermistors, are shown in the vicinity of the electrodes (25). Moredetail regarding the particular size, material, dimensions, and methodsof constructing the electrode and temperature monitoring elements onto acatheter as just described may be found by reference to U.S. Pat. No.5,582,609 to Swanson et al., which has been previously incorporated byreference.

Furthermore, the temperature monitoring elements may be either coupleddirectly to the electrodes, or may be otherwise positioned along thelength of the ablation element as would be apparent to one of ordinaryskill. For example, FIG. 14 shows such an alternative arrangement ofthermocouples (27′) between adjacent electrodes (25) along the ablationelement (121).

The electrode and temperature monitoring designs just described merelyrepresent specific embodiments for use with the broader presentinvention. Additional suitable ablation elements are described above inoverview fashion by reference to prior known references, the disclosuresof which have been incorporated by reference. In particular, however,more detailed examples of coiled electrodes coupled with temperaturemonitoring mechanisms for use in the current invention are described inU.S. Pat. No. 5,582,609 to Swanson et al., which has been previouslyincorporated by reference above.

More detail regarding suitable examples for an ablation actuator for usewith the ablation element embodiments herein described is provided byreference to the schematic depiction of ablation actuator (90) in FIG.15A. Ablation actuator (90) in the FIG. 15A variation includes a currentsource (92) for supplying an RF current, a monitoring circuit (94), anda control circuit (96). The current source (92) is coupled to theablation element (not shown) via the electrode leads in electricalcoupler (51), and is also coupled to the ground patch (98). Monitoringcircuit (94) is coupled to the thermistor leads in electrical coupler(51), and also to control circuit (96). Control circuit (96) is in turncoupled to both the monitoring circuit (94), and also to the currentsource (92) in order to adjust the output level of current driving theelectrodes based upon the relationship between the monitored temperatureand a predetermined temperature set-point.

The feedback control circuit just described is therefore based uponcomparing the measured, real-time temperature of the ablation regionagainst values known to indicate ablation progress. A monitoredtemperature may for example signal the completion of ablation andtherefore trigger cessation of energy delivery. Or, such values mayindicate the quality of tissue contact, which information may be used inthe control circuit to adjust the drive current to the region at issue.Furthermore, a particular set-point may be predetermined based uponknown empirical values, or may be patient dependent, as would beapparent to one of ordinary skill.

In addition to, or in the alternative to the temperature controlfeedback mechanism just described, it is further contemplated that theelectrical parameters of the RF ablation drive circuit may be monitoredin order to provide suitable feedback control. For example, outputvoltage, output current, output power, impedance, or reflected power, orchange or time rate of change of these parameters may be monitored andused in one or a series of feedback control algorithms. The real-timevalue of such monitored parameters have been observed to characterizethe progress of some ablation procedures, and have also been used incontrol circuits for real-time feedback control of ablation drivecurrent.

Each individual electrode of the plurality of electrodes in the ablationelement may also be individually controlled in a control system, such asin a multiplexed system. One example of a feedback control system whichis believed to be suited for such feedback control of the ablationelements provided with the present invention is described in WO 96/00036to Panescu et al. Further examples of feedback control systems which maybe adapted for use in the present invention according to one of ordinaryskill based upon this disclosure are provided in U.S. Pat. No. 5,496,312to Klicek; U.S. Pat. No. 5,437,664 to Cohen et al.; and WO 93/20770 toStrul. The disclosures of the feedback control references just describedare herein incorporated in their entirety by reference thereto.

Long Linear Lesion “Box” as Conduction Block

FIGS. 16-21 show the device assembly of the current invention in varioussteps during the completion of an overall atrial fibrillation treatmentprocedure, wherein a box configuration of conduction block is createdaround the region of the pulmonary vein ostia. Throughout thisparticular subset of figures, an atrial lesioning catheter deviceassembly similar to that shown in FIG. 5 is shown, for purposes ofillustration, in various positions within a sectioned left atrium duringsequential lesion formation between various predetermined pairs ofpulmonary vein ostia.

FIG. 16 shows tissue ablation device assembly (301) after performing afirst long linear lesion ablation procedure with the ablation element(320) of ablation catheter (302) positioned in a first position betweenthe left and right superior pulmonary vein ostia (383,384) (firstposition not shown in this figure). In this figure, ablation catheter(302) is shown repositioned in a second position between the leftsuperior and inferior pulmonary vein ostia for performing a long linearlesion ablation procedure between that pair of adjacent vein ostia.

FIG. 17 shows the ablation catheter (302) in the left atrium afterperforming a second long linear lesion ablation procedure according toFIG. 16, wherein the ablation element (320) is repositioned to a thirdposition where its ends are anchored in the right superior and inferiorvein ostia (384,385). Subsequent to performing this third linearablation, an open ended box of lesions results between all adjacentpairs of vein ostia, but between the inferior vein ostia. This resultmay sufficiently treat some atrial reentrant fibrillation sequelae, asmay any of the other interim results subsequent to each ablationlesioning step described for this procedure.

However, it is believed that many patients with multi-wavelet reentrantatrial fibrillation require complete isolation of the pulmonary veinostia from the other atrial tissue. While one mode of achieving suchcomplete isolation may be to connect the final leg of the conduction“box” between the inferior vein ostia, an alternative solution offorming a pair of lesions between these ostia and the mitral valveannulus at the base of the left atrium is also believed to bereasonable.

FIGS. 18 and 19 therefore show sequential steps in forming a pair oflesions between the inferior pulmonary vein ostia and the region oftissue adjacent to the mitral valve annulus. More particularly, FIGS. 18and 19 provide a schematic representation of the intracardiac placementof two monopolar electrodes that are combined in a bipolar cardiacablation arrangement which is adapted to form ablation lesions betweenthe inferior pulmonary vein ostia and adjacent regions of the mitralvalve annulus.

In FIG. 18, a first monopolar ablation electrode element (392) is shownpositioned adjacent to the left inferior pulmonary vein ostia (386). Aswould be appreciated by one of ordinary skill, this electrode may takemany suitable forms in this application regarding its incorporation ontovarious catheter platforms, and is therefore represented schematically.In one exemplary mode not shown, the electrode may be at least one ofthe electrodes along the length of an ablation element as provided inthe previous variations of the invention. For example, the electrode maybe at the end of an ablation element adjacent to the catheter's mostdistal end, such as the electrode shown between guidewire ports (332)and (334) in FIGS. 16 and 17. In this example, the electrode may bepositioned within the inferior pulmonary vein ostium as would beapparent to one of ordinary skill according to the teachings of thevariations above.

A second ablation electrode element (395) is also shown in shadowed viewin FIG. 18 positioned within the coronary sinus (396) and is positionedalong that lumen such that it is adjacent to the first electrode element(392). Again, this electrode may comprise one of several known electrodeconfigurations and be sufficient for the purposes of this bipolarablation step, hence the schematic representation in the Figure.

The second ablation electrode element (395) is positioned in thecoronary sinus as follows. Initially, a guiding catheter is introducedinto the right atrium either via the superior or the inferior vena cavaeaccording to known methods (and according to some of the same methodsdescribed in more detail above). Next, the device is introduced throughthe guiding catheter and into the coronary sinus through its ostium inthe right atrium, which may be accomplished by tracking the secondelectrode carrying device (394) over a steerable guidewire which haspreviously sub-selected the coronary sinus distally of the guidingcatheter. Or, in the alternative, the guiding catheter or a secondguiding catheter within the original guiding catheter may be shaped andotherwise adapted to engage the coronary sinus ostium along the rightatrial wall and thereby provide a lumenal conduit into that vessel.

Once in the coronary sinus, the second electrode (394) may be positionedrelative to the first electrode using a variety of techniques. In onevariation, the electrical potential between the two electrodes mayprovide a measure of their relative distance from each other. Thismeasure may provide a telling inflection point as the second electrodeis advanced through the coronary sinus and across the position closestto the stationary, anchored first electrode. In another variation, thefirst and second electrodes are each sufficiently radiopaque such thattheir relative distance from each other is easy to visualize via Xrayfluoroscopy.

Regardless of the particular makeup of the electrodes or mode ofdirecting and fixing their relative positioning, once so positioned anelectrical signal transmitting therebetween serves to ablate the atrialwall tissue therebetween, as would be apparent to one of ordinary skill.

FIG. 19 shows a similar schematic view of first and second electrodedevices as that shown in FIG. 18, although showing the devices in asecond position wherein they are collectively adapted to ablate a longlinear lesion between the right pulmonary vein ostium (385) and anadjacent region of the mitral valve annulus (388). In this figure, along linear lesion is shown between the left pulmonary vein ostium (386)and an adjacent region of the mitral valve annulus (387) subsequent toits formation according to the device positioning of FIG. 18. As will beappreciated by one of ordinary skill, the lesioned “box” is thuscompleted by forming long linear lesions between and connecting theinferior pulmonary veins with the region of the mitral valve annulus.

FIG. 20 shows further a device assembly of the current invention in asingle positioning event during an atrial fibrillation treatmentprocedure, wherein at least a portion of a conduction block is createdaround the pulmonary vein ostia and the mitral valve annulus in anassembly shown in a similar, reciprocal image as that view shown in FIG.7. In this Figure, however, tissue ablation device assembly (301) isused to create multiple long linear lesions with various adjacentlypositioned ablation elements along its body and. In one aspect of thisassembly, an ablation element (320) has each of two ends anchored in thetwo adjacent superior vein ostia (383,384). In a further aspect, asecond ablation element (325) is provided proximally of the anchorengaged to left superior ostium (383) and is anchored distally by thatsame anchor and more proximally is positioned against the wall via ashaped stylet (305). Further to this aspect, shaped stylet (305) isadapted to impart a shape to the catheter shaft in the region of thesecond ablation element such that the shaped region of the ablationelement substantially conforms to the tissue of the adjacent atrialwall. Still further, stylet (305) adaptes the region of the secondablation element to traverse the left inferior pulmonary vein ostia(386) to the region of the coronary sinus so as to engage the mitralvalve annulus. In this manner, a single continuous long linear lesion iscreated.

In a further inferior vein ostium-mitral valve annulus lesioningvariation not shown, it is further contemplated that a guidewire may beadvanced antegrade from the left atrium and through the mitral valveinto the left ventricle. In this manner, a rail is provided into theregion of the mitral valve such that a correspondingly engaged guidewiretracking member on the tissue ablation catheter assembly according tothe invention may be placed through the valve to anchor the ablationelement against the mitral valve annulus.

Still further, in a retrograde arterial access approach to introducingthe devices herein described into the left atrium, a guiding cathetertip is advanced into the left atrium through the mitral valve. It isalso contemplated that that guiding catheter tip region may provide anadditional ablation element to assist in completing the inferior leg ofthe barrier-to-barrier conduction block described by ablating a regionbetween the inferior vein ostia and the mitral valve annulus.

Regardless of the specific variation applied, the purpose of furtherillustration, FIG. 21 shows a completed “box” of long linear lesionsformed according to the ablation catheter variations shown and describedabove, and particularly by reference to the sequential long linearlesioning methods shown and described with reference to FIGS. 16-19.

Further to the overall procedure of using the device assembly of thecurrent invention, the initial placement of the ablation catheterassembly into the left atrium may be achieved using known accessprocedures according to one of ordinary skill. Generally, theseprocedures access the left atrium either transeptally from the rightatrium through the fossa ovalis in the intra-atrial septal wall, orretrogradedly from the left ventricle and through the mitral valve (asintroduced briefly above). The embodiments shown herein in the figuresand described above have portrayed use of the present invention througha transeptal sheath approach for the purpose of consistent illustration.However, the device variations described are considered to be adapted oreasily modified according to one of ordinary skill for use in theretrograde arterial approach from the ventricle into the left atrium.Nevertheless, a brief overview of one transeptal left atrial accessprocedure through the fossa ovalis is herein described for the purposeof providing a thorough understanding of an acceptable access method.

Initially, the right atrium is accessed with a guiding catheter orsheath through either the inferior or superior vena cava, whichinitially requires cannulation with an introducer sheath such as throughthe well known “Seldinger” technique.

Suitable guiding catheters for use in this procedure are also wellknown, but generally range from 7 to 12 French, preferably 8 to 120French, and include shaped, radiopaque tips and torqueability for thepurpose of steering and directing the catheter to the desired remote invivo locations under Xray fluoroscopy. Importantly, at least one largelumen is provided in the guiding catheter for the purpose of providing atubular conduit for the delivery of various object devices for treatmentonce properly located. Generally, a guidewire such as a 0.032″ diameterguidewire is also provided coaxially within the guiding catheter lumenin a telescoping arrangement, also for aiding the directing the guidingcatheter to the target site.

Once in the right atrium, the guiding catheter is directed toward thefossa ovalis, and is advanced through that septal opening to finallycannulate the left atrium and provide lumenal access into that bodyspace to direct object treatment or diagnostic devices thereto. Theaccess through the fossa ovalis may be achieved by advancing a“Brockenbrough” needle or trocar through a dilator, which assembly isagainst the fossa ovalis through the guiding catheter. The needle,dilator, and guiding catheter are then advanced through the fossaovalis, after which the needle and dilator are withdrawn to leave theguiding catheter in place.

It is further contemplated that various diagnostic and other patientmanagement regimes may be required ancillary to creating long linearlesions for treating left atrial fibrillation according to the currentinvention. For example, it is contemplated that several diagnosticprocedures may be necessary prior to successfully performing the longlinear lesioning treatments just described.

For example, patients are known to differ in their anatomical make-up inthe region of the pulmonary vein ostia. More particularly, Jafs et al.in a scientific abstract entitled, “Biatrial Dimensions Relevant toCatheter Ablation”, North American Society of Pacing andElectrophysiology, 17th Annual Scientific Sessions Abstract Form, haspreviously disclosed finite ranges of distances between the variouspairs of adjacent pulmonary vein ostia among human left atria. Basedupon that disclosure, the range of distances between the superiorpulmonary vein ostia is believed to be 31 to 55 millimeters (mean of43+/−8 millimeters); and the range of distances between the superior andinferior pulmonary vein ostia is 25 to 46 millimeters (mean of 38+/−7millimeters).

According to these ranges, providing only one length of ablation elementaccording to the present invention may negate a sizeable, otherwisetreatable patient population. It is contemplated that a kit of ablationcatheter device assemblies may be required which includes variouslengths of ablation elements between anchors. For example, providing akit with available ablation elements having lengths ranging fromapproximately 15 millimeters to approximately 70 millimeters, andpreferably ranging from approximately 25 millimeters to approximately 55millimeters, may provide a suitable range to choose from in order totreat most patients. Furthermore, it is contemplated that quantitativepulmonary angiography and/or transesophageal echocardiography mayprovide sufficient diagnostic tools for measuring a patientsinter-pulmonary vein ostia distances prior to long linear lesioningtreatment. The kit will also typically include appropriate packaging forthe individual devices and instructions for operation and use.

In still another procedural aspect of the current invention, patientsreceiving the long linear lesioning treatment described for the presentinvention may benefit from the administration of various anticoagulantssuch as Cumidin and/or Heparin.

It is to be understood from the disclosure above that that particularvariations of a broader invention have been described. Additionalmodifications or variations other than those particularly described maybe made based on this disclosure according to one of ordinary skillwithout departing from the scope of the following claims.

1. A tissue ablation device for creating long linear lesions in thetissue of a body space wall which defines at least in part a body spacein an animal, comprising: an elongate body having proximal and distalend portions; an ablation element on the distal end portion and havingfirst and second ends, said ablation element being adapted to ablatetissue when coupled to an ablation actuator; a first anchor adjacent thefirst end which is adapted to secure the first end at a predeterminedfirst location along the body space wall; and a second anchor adjacentthe second end which is adapted to secure the second end at apredetermined second location along the body space wall, wherebysecuring the first and second ends to the predetermined locations withthe anchors, said ablation element is adapted to substantially contact alength of said tissue adjacent to the ablation element and between thefirst and second locations without substantially repositioning thedistal end portion of the elongate body. 2-80. (canceled)